The present invention relates to a fuel injection device for spark-ignition internal combustion engines.
More particularly, it relates to such a fuel injection device which has a pump and a distributor driven at a pump speed wherein a rotating part of the distributor alternatingly connects a feed line connected with the pump with injection lines leading to individual cylinders of the internal combustion engine as a function of the angle of rotation.
In a fuel injection device known from EP-PS 0 114 991 for spark-ignition internal combustion engines of this type the dwell time of the fuel in the combustion chamber during full-load operation of the internal combustion engine is lengthened compared to the dwell time during partial load operation by the 180.degree. angle of rotation of a camshaft connected with a combustion engine piston. The amount of fuel injected is adapted to the load operation. For this purpose, the fuel injection device has a pump and a distributor which is preferably driven at pump speed. The rotating part of the distributor alternately connects a feed line, which is connected with the pump, with injection lines leading to the individual cylinders of the internal combustion engine via inner through-ducts as a function of the angle of rotation.
During full-load operation of the internal combustion engine the fuel is introduced into the combustion chamber during the suction stroke of the combustion engine piston so that this fuel can be thoroughly mixed to the time of ignition. In this way a complete combustion of the fuel-air mixture is ensured and soot emissions are prevented. On the other hand, during partial load operation of the internal combustion engine the fuel is injected very late, i.e. immediately before the time of ignition, so that an ignitable mixture can be formed in the area of the spark plug in a layered manner and the inflammation initiated by the spark plug immediately accounts for the remaining charging of the combustion chamber.
A reversing valve is provided for switching between the two different load-dependent injection times of the fuel injection device. Two inlet openings can be connected with the pump work space in an alternating manner. The outlet side has two outlet openings which are connected with the inlet opening depending on the position of the valve slide. The outlet openings lead to two different inner passage ducts of the rotating part of the distributor. The openings of the two passage ducts occupy different angular positions in the stationary part of the distributor so that the resulting two opening angle areas of the rotating part of the distributor lead or lag behind relative to one another with reference to the respective cylinder of the internal combustion engine.
The differently timed injection depending on the angular opening area is effected depending on which opening is connected with the inlet opening of the reversing valve by the reversing valve for the injection of fuel. Corresponding annular grooves assigned to the lines are provided for feeding the fuel from the reversing valve via lines into the through-ducts of the rotating part of the distributor. The fuel accordingly flows from the reversing valve, via the connected annular groove, into the corresponding through-duct and further, via its opening, into the respective injection line connected with a cylinder.
The method for load-dependent injection of fuel into the combustion chamber of the internal combustion engine achieved with the known fuel injection device has proven successful due to the savings on fuel and the reduced pollutant emissions resulting from this, but the construction of the fuel injection device is not optimal.
On the one hand, the known fuel injection device has the disadvantage of a complicated construction. In particular, it is costly to manufacture the numerous transitions for the fuel between the fixed part of the distributor and the rotating part of the distributor. For trouble-free operation, these fuel transitions which are constructed as annular grooves require exact manufacturing with low tolerances of the distributor parts and providing corresponding sealing means.
Moreover, the rotating part of the distributor has no homogeneous distribution of mass due to its internally extending through-ducts with the corresponding inlet and outlet openings at the surface of the rotating part of the distributor.